Prior casters have provided arrangements where a supporting wheel, or floor engaging element is rotatably mounted on an inclined axle offset from a vertical pivot axle about which the caster swivels. In such designs the caster consisted of a pair of complemental hemispherical, opposed casting sections to form a generally enclosed hollow shell wherein one of the casting sections was relatively fixed on the vertical pivot and the other casting section constituted the rotatable wheel, or floor engaging roller. Tilted axle casters of this general type permit the hollow shell to swivel about the vertical axle. However, the enclosing sections have always been made up of castings and while they have been made from die castings they necessarily were relatively heavy and consequently costly, both from the standpoint of the casting processes involved and the necessity for sufficient strength in the completed caster to support the relatively heavy loads which the casters were adapted to carry. The amount of material in such casters has become burdensome from a cost standpoint with the constantly increasing cost of materials and as a consequence competitive advantages of casters of superior design are on the verge of being lost to competitive casters and particularly with the advent of the expiration of basic U.S. patents, from foreign competition where producers are able, with lower labor and material costs to furnish a proven caster structure from an expired U.S. patent and thus provide a good caster of fully developed design without having any of the development costs ordinarily entailed in the production of a caster of competitive quality. Such casters can be sold for less than the price of a domestic product which has been developed and produced on the basis of all normal costs included in the marketing price of the caster. Consequently, it has become necessary to reduce the costs involved in producing a caster of new and improved design and representing a suitable structure able to compete on the basis of price as well as quality.